diff options
| author | Robin Gong <b38343@freescale.com> | 2014-07-11 17:47:17 +0800 |
|---|---|---|
| committer | Fugang Duan <b38611@freescale.com> | 2014-07-14 13:08:57 +0800 |
| commit | f7c1dc0720d1f6f9bbe732c67a9115887d6b05d4 (patch) | |
| tree | 489e7a2da8b158be151cde9a5931eda1f6e2044e | |
| parent | 01864d57b3f15c3ed84a53da1c55368cdd9202c7 (diff) | |
ENGR00322581-03 tty: serial: imx: start rx_dma once RXFIFO is not empty
Start rx_dma once RXFIFO is not empty that can avoid dma request lost
and causes data delay issue.
Signed-off-by: Robin Gong <b38343@freescale.com>
Signed-off-by: Fugang Duan <B38611@freescale.com>
| -rw-r--r-- | drivers/tty/serial/imx.c | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index 81ee2f23d0a8..c73c05b33c49 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -936,8 +936,21 @@ static void dma_rx_callback(void *data) tty_flip_buffer_push(port); start_rx_dma(sport); - } else + } else if (readl(sport->port.membase + USR2) & USR2_RDR) { + /* + * start rx_dma directly once data in RXFIFO, more efficient + * than before: + * 1. call imx_rx_dma_done to stop dma if no data received + * 2. wait next RDR interrupt to start dma transfer. + */ + start_rx_dma(sport); + } else { + /* + * stop dma to prevent too many IDLE event trigged if no data + * in RXFIFO + */ imx_rx_dma_done(sport); + } } static int start_rx_dma(struct imx_port *sport) |